Method of and apparatus for polishing



April 12 1927.

W. TAYLOR ETAL METHOD oF AND APPARATUS FOR POLISHING Filed Feb. 21. 1922 3 Sheets-Sheet 1 Altomey April 12 1927.

Filed Feb. 2l. 1922 5 Sheets-Sheet 3 ffffffff v' E) (i .I TlME y? ii l1 l JE- l fz/ g llll lllll v 4.nu `.nu ||||||||n||m|||||||||| i 9mm l Patented Apr. 12, 1927.

UNITED sTATEs WILLIAM TAYLOR AND FRANCIS WILLIAM PRESTON, OF LEICESTER, ENGLAND.A

METHOD OF AND APPARATUS FOR POLISHING.

Application led February 21, 1922. Serial No. 538,283.

This invention relates to a method and apparatus for polishing, and more specifically for polishing glass and like substances, and aims to provide al method and means whereby more eiiicient and economical' polishing .may besecured through suitable regulation of the amount of polishing material maintained between the coacting surfaces of a polishing member andthe work.

In machines customarily used for polishing glass in which a relative movement is eiected between the coacting surfaces of a polishing member and the work, the polishing is accomplished by means of an abrasive powder, such as rouge. which is supplied so as to enter between the polishing member, the face of which may consist of felt or other suitable material, and the surface to be polished. The abrasive is customarily suspended in a liquid" vehicle, or lubricant, such as water, and sometimes part of the water is supplied separately.

The eiciency of the polishing de ends upon the amount of abrasive materia and amount of Water or other lubricant present between the polisher and the work. The amount of abrasive and amount of lubricant present also determine the frictional resistance between the coacting surfaces of the work and polishing member. In general, so

'long as the amount of liquid present is suitable, increase in the amount of abrasive present increases the friction, While too little abrasive decreases the rate of polishing and decreases the friction. On the other hand, in general, decrease in the amount of liquid between the` polisher and the work increases the friction, whilel increase in the amount of liquid reduces the friction: It is generally necessary to limit 'the friction not to exceed a predetermined maximum in order to avoid displacement of the work or for other reasons. In order to obtain the most efficient polishing, having regard to the rate of polishing, power consumption, and con# sumption of abrasive, the frictional resistance between the polishing member and the work should be maintained at all times during an operation as near as may be to such maximum, and it may in practice be allowed to vary within a predetermined range below said maximum. To this end the supplies of abrasive and lubricant must be maintained within suitable limits.

In an application of William Taylor, led

May 17, 1919, Serial No. 297,777, there is described and claimed a method and apparatus wherein the supply of lubricant or lubricant and abrasive is regulated according to variations in frictional resistance between the coacting surfaces of the polishing -member and the work in order to maintain the frictional resistance substantially constant or lwithin a limited range of variation. Said application also describes and s eciiically claims a method and meansw erein the above result is Vsecured by causing the variation of frictional resistance between the surfaces of the Work and polishing member to automatically' control and vary the supply of lubricant or Ilubricant and abrasive.

i In some cases it is convenient not l,to have the action automatic throughout, and according to the ypresent invention the variations of traction are caused to effect the operation of a suitable indicating means, and an operator controls manually the supply .of lubricant or abrasive, or both, 1n accordance with the indications of such indicating means. The indicating means is most desirably a recording device" whereby a continuous lrecord or graph of the frictional resistance during the whole polishing operation or so much thereof as may be desired is provided. Such a record gives more information as to the condition of the polishing material between the coacting surfaces than a nonrecording indicator.

The apparatus features of the invention may be incorporated in ,glass polishing machines of many diferent types. For the sake of illustration, however, we have in the accompanying drawings illustrated the application of the invention to a known e of polishing machine which is used for t e.

polishing of plate glass. A full understanding of the invention considered from both its method and its apparatus sides can best be given by a description of the illustrative machine shown in the drawings and the operation and use thereof.

In the drawings: Fig., 1 is a sectional plan view of a plate glass polishing machine incorporating the apparatus features of the invention and adapted for use in practicing the method, the view being taken on line 1-1 of Fig. 2; Fig. 2 is a view of the machine in elevation Vwith parts inL section and parts omitted; Fig. 3 is a view on a larger scale of one of the recorder operating levers; i

Fig. 4 illustrates a graph made by one of the recorders; and Fig. 5 is a fragmentary view showing another form of indicating means.

The machine shown in the drawings comprises a circular horizontal work holding` table on which the plate or plates A to be polished areplaced and suitably secured, as by means of plaster of Paris land pegs` in the usual manner. The t ble is mounted on. a vertical shaft 11 and's rotated by a driven gear 12 meshing with a gear 13 on' the shaft 11. A plurality of polishing members or units are mounted abovethe table each comprising a rotatable frame or Spider 15 carried on the lower end of a vertical shaft 16. Each frame carries aplurality of rotatable disc shaped felt covered polishing blocks 17 each carried on the lower end of a spindle 18 rotatably and slidably mounted in the frame so that the blocks may rest on the surface to be polished when' the machine is in operation. The spindles 18 are provided with means for limiting their downward movement when the frame is raised or the ltable is lowered. Four suchV polishing members or units are customarily providedl as shown and are of different sizes carrying different numbers of blocks 17, the larger unit extending from slightly beyond the edge to past the center of the table. Upper and lowerybearings for each frame shaft 16 fin which the shaft is4 free to turn are protion and at anarbitrary rate dependent on the operators judgment. ,In operating in this way the most efficient polishing is not obtaine In the machine shown, the construction is such that when the frictional resistance between the work and the polishing blocks of any one of the polishing members or units exceeds a predetermined value a yielding partwill be moved to effect the operation of an indicating device. For this purpose, as shown, the lower bearing/25 of each of the shafts 16 is carried by an arm 26 which extends in a direction which is radial from the axis of the table` and is elastic sd slightly flexible, so that the bearing 25 is capable of'y a slight movement against the elastic resistance of the arm 26'in the direction of ,-which the the mnvement of the portionof the table 10 directly below the bearing. Such movement of the bearing or arm controls the operation of a device for indicating variations each polishing member or unit through a discharge nozzle 'or pipe 35 controlled by a manually operable valve 36 and leading off most desirably from a supply pipe 37 in polishing materia-l is kept in circulatlon. v

The operation is as follows: Thetable 10 being in rotation, the friction between the plate A on the table and the polishing blocks 17 because of the varying rate of movement of the workl at different' distances from the axis of the table causes each of the polishing blocks to rotate on its spindle and at the same time causes eac-h of the frames 15 forming with its group of polishing blocks one of the polishing members 'or units to rotate about its shaft 16. The friction between the work and the blocks also tends to move each polishing member in the direction in which the table moves beneath such member, and

this drag on the member causes a stress on its lower shaft bearing 25 in the direction of movement of the tablebeneath the bearing. This stress causes a slight movement of each oflhe bearings 25 against the elastic resistance' of its supporting arml 26, the amount of which movement 'varies according to the amount of frictional resistance between the` polishing member and the work Such movement of thebearing is recorded by its recording device 30, and the supply of polishing material `is manually regulated through the valve 35 in accordance with the variation in such frictional resistance as shown by the recording device. For examp1e,if the recording device shows that the frictional resistance has increasedy above a predetermined value, the supply of polishing material will be turned on or increased by the operator, and as the frictional resistance isshown to decrease again or reaches apredetermined lower limit, the supply is diminished or eut od. 0r again if the graph is of the character shown in Fig. 4, in which as the polisher becomes' dry the frictional resistance increases up to a point X, falls` od somewhat at Y and then increases at Z, it

.may indicate that the polisher has become and increase .the supply of water.

vmeans supplied to the slightly igeaaaeo overloadedl with ji.ouge and accordingly fthe the polishing memberto make' acontinuous operator will diminish the supply' of rouge" a non-recording indicating' movable lower bearing of one of the shafts 16. Theindicating means here shownvis electrical and comprises a lamp or bell 40 and afsource of current 4l. The lamp or bell 40 and the source of lcurrent are connected so that the circuit through. them may be completed by, an adjustable circuit closing device operated by the movement of the bearing 25 when the frictional resistance between the polishing member and the wrk reaches a' predetermined value An additional lamp or "bell, 43 may also be provided, the circuit throughl which is closed by a circuit closingdevice 44 operated by the bearing 25 when the'frictional resistance is decreased to a predetermined lower value. The circuit closing devices are adjustable for varying the resistance value at which each will be operated.

From the indications given Fig. 5 shows by such signal devices the supply of polishing material may s be regulated by the operator to maintain the frictional resistance substantially constantv or within a desired limited range.

As the polishing material "is more or less evenly over the work onthe table 10 4by the rotation of the table and the polishing ,members the polishingmaplied to the work atasingle point, and this single supply may be regulated in accordance with indicating means controlled accordin to the frictional resistance between the wor and any one of the polishmembers. Controlling or varying the supply of polishing material, Aas such expressions are used herein, include controlling or varyin the rate of supply of the polishing materia as a whole when composed of abrasive and lubricant or of either component thereof;

What is claimed is: Y 1. The method of controlling the supfply of polishing material in polishing a sur ace by means of a polishing member, said polishing member and the work being moved relato one another to effect the polishing, which method comprises utilizing the variation` of frietional resistance between the surterial may be sup faces` of the work and` polishing 'member to cause the operation of an indicator,l and manually varying thesupply of polishing material according to indications of the indicator.

ance between the surfaces ofthe work and polishing members and means :operated by variation of the 'tween said surfaces to cause distributed record of 'the variation in the friction,- and manually controlling the supply of polishing material according to said record. 3; The combination with a polishing machine having cooperating work-holding and -foi` causing n for producing relative movement .between the coacting surfaces of the polishing member and the work, of means for supplying polishing material to saidsurfaces, manually operated means for controlling the-supply of polishing'material, an indicator, and means friction bethe indicator to indicate to an operator of the controlling means whe/n the friction betweensaidsurfaces reaches a predetermined value.

4. The combination with a polishing machine having cooperating work-holding and polishing 'members and means for causing relative motion between said members for *movement between the and `the work, of means for suppl polishing :material to said surfaces, a recorder, and the friction between said surfaces to cause the recorder to make a continuous record of the variation ,of such friction.

5. The combination with a polishing machine having cooperating Work-holding and rs and meansf or causing-- polishing membe relative motion between said members for [producing relative movement. between the' operated by variation in the friction lbemeans operated by variation in tween `said surfacesto cause the recorder to make aI continuous record of the amount of said friction, the recorder being positioned lso that the record being made thereby is visible to an operator of tsaid controlling means.

6. In a polishing machine, comprising a polishing member, a work-holding member, and driving means for moving one o said members to cause' relative movementy between the coacting surfaces of the polishing member and the work, indicating means for indicating variations -in the friction between the said surfacesactuated by such friction independently of other components of the load on said driving means. `f

7. In a polishing machine, comprising s polishing member and a work-holdingmem ber, means 'for moving one of said' members and means for constrainingvthe other o' said members against movement by the fric tion between the coacting surfaces `of t polishing member and the work,

bination4 of a yieldable element in said constraining means adapted to yield when the said friction reac es a predetermined value, and indicating means actuated by the yielding of said yieldable element. s

In a polishing machine, comprising a work-holding member, a plurality of polishing members, means for causing a relative movement between the polishing member and predetermined value.

In a polishing machine comprising a work-holding member, a plurality of polishto lndicate to the operator of said fwhereof, We have hereunto 

